Charmonium spectroscopy and mixing with light quark and open charm states from nF=2 lattice QCD

We study the charmonium spectrum including higher spin and gluonic excitations. We determine an upper limit on the mixing of the eta(c) ground state with light pseudoscalar flavor-singlet mesons and investigate the mixing of charmonia near open charm thresholds with pairs of (excited) D and (D) over bar mesons. For charm and light valence quarks and n(F) = 2 sea quarks, we employ the nonperturbatively improved Sheikholeslami-Wohlert (clover) action. Excited states are accessed using the variational technique, starting from a basis of suitably optimized operators. For some aspects of this study, the use of improved stochastic all-to-all propagators was essential.